It depends on the relationship you have with a guy. If its a guy who you feel there is a mutual attraction with, it could means he likes you. Yes, he could just be pleased to see you, but most guys won't light up due to see just another girl.
Your (lack of) punctuation makes your message hard to follow.
Given that, I'll see what I can do.
Based on my experience, I'd have to agree not reading anything into it.
Let me clarify that. My daughter has a friend who is a lesbian. I had this preconceived idea that all lesbians are 'bull dykes', but I really like this girl. Whenever I see her, I light up, and I believe she sees it.